ISPs are sabotaging this stuff so people will buy their stuffty dedicated phone service.
There should be a Survey asking people what their ISP is and if they have Drops in online calls.
But I can safely say that when i used VPNs and I was also using Comcast my skype calls ran better, and this was before the whole end of Net Neutrality.
Although usually my calls would drop anyway due to comcast's internet just dropping entirely.
Seriously forget comcast.